ICR mass spectrometry

J. Laskin and J. H. Futrell. Activation of Large Ions in FT-ICR Mass Spectrometry. Mass Spectrom. Rev., 24(2005) 135-167. 

The gas-phase reactions of the fulvene radical cation with neutral 1,3-butadiene, alkenes and 2-propyl iodide have been investigated by Russell and Gross131a using ICR mass spectrometry. Unlike ionized benzene, ionized fulvene undergoes no C—C coupling with 2-propyl iodide. On the basis of deuterium and 13C labelling, the reaction of ionized fulvene with 1,3-butadiene was suggested to occur by [6 + 4] cycloaddition to yield tetrahydroazulene radical cations. Cycloadditions of neutral fulvene were also studied in this work. 

Decarboxylation of 1,3-dimethylorotic acid in the presence of benzyl bromide yields 6-benzyl-1,3-dimethyluracil and presumably involves a C(6) centered nucleophilic intermediate which could nonetheless have either a carbene or ylide structure. Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry has been used to explore the gas-phase reactions of methyl nitrate with anions from active methylene compounds anions of aliphatic ketones and nitriles react by the 5n2 mechanism and Fco reactions yielding N02 ions are also observed nitronate ions are formed on reaction with the carbanions derived from toluenes and methylpyridines. 

The majority of H/D studies that have been reported employ quadrupole ion trap (QIT) instruments due to their ease of use, excellent sensitivity, ability to perform MS/MS experiments, compact size, and low cost. Other reports discuss the use of instruments with higher mass-resolving power such as the hybrid QqTOF instruments [47]. A few groups have utilized FT-ICR mass spectrometry, which offers ultra-high mass-resolving power and improved mass accuracy [48, 49]. 

Several studies have examined the reactions of Mg+" with unsaturated molecules. Under the lower pressure conditions of FT-ICR mass spectrometry, Mg+" reacts with the polycyclic aromatic hydrocarbon, coronene, via a combination of radiative associative adduct formation (equation 16) and electron transfer (equation 17). The latter reaction is 8 times faster, consistent with it being exothermic. Adduct formation (equation 16) also readily occurs in reactions with Theoretical calculations suggest that related radiative... 

The gas-phase ionization of 2,4,6-tribromobenzene in the presence of m-fluoropyridine afforded the A -aryI -m-fluoropyridinc adduct from which the biradical cation was generated by loss of two bromine radicals.232 This biradical species was isolated and characterized using Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry and its chemical properties are discussed. FT-ICR was also used to isolate and characterize the products of electron ionization of fluorinated acetyl compounds, which included a biradical anion.233... 

Fornarini, Matire, and co-workers110 have recently used Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry assaying the multiphoton dissociation behavior (IR-MPD) of the C3H7+ ion. This study has confirmed the conclusions of the computational results discussed above. The IR spectra recorded in solution and in a solid matrix display close resemblance to the spectral characteristics found by the IR-MPD study. Theoretical studies also indicated that the virtually free methyl rotation allows the interconversion of the two enantiomers of the isopropyl cation. 

Identification of fulleranes by Raman spectroscopy and XRD is difficult due to complexity of obtained mixture. Precise determination of composition for white colored fullerane samples was performed using APPI FT-ICR mass spectrometry. 

Fu, J., Klein, G. C., Smith, D. F., Kim, S., Rodgers, R. R, Hendrickson, C. L., and Marshall, A. G. (2006a). Comprehensive compositional analysis of hydrotreated and untreated nitrogen-concentrated fractions from syncrude oil by electron ionization, field desorption ionization, and electrospray ionization ultrahigh-resolution FT-ICR mass spectrometry. Energy Fuels 20,1235-1241. 

The analytically important features of Fourier transform ion cyclotron resonance (FT/ICR) mass spectrometry (1) have recently been reviewed (2-9) ultrahigh mass resolution (>1,000,000 at m/z. < 200) with accurate mass measurement even 1n gas chromatography/mass spectrometry experiments sensitive detection of low-volatility samples due to 1,000-fold lower source pressure than in other mass spectrometers versatile Ion sources (electron impact (El), self-chemical ionization (self-Cl), laser desorption (LD), secondary ionization (e.g., Cs+-bombardment), fast atom bombardment (FAB), and plasma desorption (e.g., 252cf fission) trapped-ion capability for study of ion-molecule reaction connectivities, kinetics, equilibria, and energetics and mass spectrometry/mass spectrometry (MS/MS) with a single mass analyzer and dual collision chamber. 

The basic principle of FT/ICR mass spectrometry is that a moving ion in an applied static magnetic field undergoes circular motion, in a plane perpendicular to that field, at a "cyclotron" frequency, U3 ... 

Most analytical studies using FT-ICR mass spectrometry, where ions have been produced inside (or just outside) the analyzer cell, have used lasers as ionization sources. Other than some very limited Cs secondary ion mass spectrometry (SIMS) studies [77], most research utilized direct laser desorption to form various organic [78] and inorganic [79] ions, including metal [80] and semiconductor [81] (including carbon) clusters. More recently matrix assisted laser desorption ionization (MALDI) has been used to form ions of high molecular weight from polymers [82] and many classes of biomolecules [83]. 

ICR mass spectrometry has been employed to study the kinetics and equilibria of the generation of silylenium ions by hydride transfer from silanes to carbenium ions (43,47). The kinetics of the formation of silylenium ions from fluoromethylsilanes [(CH3) SiF4 , n = 1-3] have also been investigated by this technique (48). Fluoride transfer was the dominant reaction in this system. 

Kinetics of the reactions of Me3Si+ with water (57) and alcohol (31,32) were investigated by ICR mass spectrometry. Proposed mechanisms involve formation of an oxonium ion as the primary product, which in the case of the methanol adduct is eventually decomposed to methoxy-silylenium ion according to Eq. (9). Reactions of halide transfer to silylenium ion [Eqs. (10) and (11)] have been studied by FT mass spectrometry (59) and by tandem mass spectrometry (44). Hydride transfer... 

The gas-phase reactivity of Ln2+ with alkanes (methane, ethane, propane, n-butane) and alkenes (ethene, propene, 1-butene) was studied by Fourier transform ICR mass spectrometry. The reaction products consisted of different combinations of doubly charged organometallic ions-adducts or... 

The reaetion between the ammonium ion, NH , and trimethylamine, (CH3)3N, analogous to Eq. (4-16), has been studied by pulsed ICR mass spectrometry [115]. The Gibbs energy diagram in Fig. 4-2 describes what happens to the reactants on going from... 

Three new experimental techniques, developed within the past decades, now make it possible to study ionic reactions in the gas phase as well. These are pulsed ion-cyclotron-resonance (ICR) mass spectrometry, pulsed high-pressure mass spectrometry (HPMS), and the flowing afterglow (FA) technique [469-478 see also the references given in Section 4.2.2]. Although their approaches are quite independent, the results obtained for acid/base and other ionic reactions agree within an experimental error of 0.4... 1.3 kJ/mol (0.1... 0.3 kcal/mol) and are considered as reliable as those obtained in solution. 

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